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The AAPG/Datapages Combined Publications Database

Journal of Sedimentary Research (SEPM)


Journal of Sedimentary Research
Vol. 74 (2004), No. 4. (July), Pages 580-598

Processes of Sediment-Wave Construction Along the Present Zaire Deep-Sea Meandering Channel: Role of Meanders and Flow Stripping

Sebastien Migeon,, Bruno Savoye, Nathalie Babonneau, France-Lucy Spy Andersson


Detailed study of fine-grained migrating sediment Previous HitwavesNext Hit and processes of sediment deposition along the modern, active, meandering channel of the Zaire turbidite system was made on recent cruises. The data used in this study include EM12 bathymetry and backscatter imagery, 3.5 kHz profiles, high-resolution seismic-reflection profiles and Kullenberg piston cores. Migrating sediment Previous HitwavesNext Hit are built under several different flow energies and hydrodynamic conditions (subcritical or supercritical condition) according to their location along the modern Zaire channel. The process of sediment-wave initiation is inferred from cores and high-resolution seismic-reflection profiles. Overflow density and sediment supply delivered to levees appear as critical parameters for wave initiation. In other cases, a preexisting wavy topography is observed that acts as a template favoring sediment-wave initiation. Core-to-core correlation between the two flanks of a single sediment wave reveals no major differences in the lithofacies, suggesting no change of the dynamics of overflows during sediment deposition on both flanks of the Previous HitwavesNext Hit. Comparison of number, thickness, and type of individual beds in cores collected on both flanks of the wave suggests that most lower-velocity and density overflows depositing sediments on the upstream flank bypass on the downstream flank. This process is probably related to a strong decrease then increase of the bed shear stress on the upstream and downstream flank of the wave, respectively. Interpretation of lithofacies suggests that construction of migrating sediment Previous HitwavesNext Hit is closely linked to repeated successive spillovers from the Previous HitheadTop and body of a single channelized turbidity current. Construction of a single wave is rapid, less than 5000 years.

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